An expert retained by the victims of the Fern Hollow bridge collapse said the three engineering firms contracted to inspect the span failed to uphold the standard of care required for professional engineers.
David B. Mrowiec, a civil engineer based in Virginia, reached that conclusion after reviewing thousands of pages of documents released by the Pennsylvania Department of Transportation, the National Transportation Safety Board and the City of Pittsburgh and examining the bridge components post-collapse at a government storage yard in Virginia.
Mrowiec’s findings were included in a court filing Monday in Allegheny County Common Pleas Court as part of ongoing litigation surrounding the Jan. 28, 2022, collapse.
Around 6:40 a.m. that day, the 447-foot bridge that connected Regent Square with Squirrel Hill collapsed into a Frick Park ravine, dropping an articulated bus and four other vehicles 100 feet. A fifth car drove off the east abutment as the bridge was falling.
Several people were injured, but no one was killed.
The victims, including the driver of the Pittsburgh Regional Transit bus, sued the city, as well as the engineering companies that had been hired to do regular inspections of the bridge built in 1970.
The case, pending before Allegheny County Common Pleas Judge Philip A. Ignelzi, is scheduled for jury selection on May 11.
In Monday’s filing by the plaintiffs, Mrowiec concluded, like the NTSB before him, that the bridge collapsed after a failure of the transverse tie plate on the southwest bridge leg.
That failure, marked by excessive corrosion and section loss, was caused by clogged bridge drains that trapped excess water runoff and de-icing salts that accumulated at the bottom of the legs.
In addition, Mrowiec said the bridge’s load rating — how much weight it could hold — had been inaccurately calculated and that there was more than double the amount of asphalt on the bridge deck as reported.
In his report, Mrowiec faulted the City of Pittsburgh, CDM Smith, Gannett Fleming and Larson Design Group.
An attorney for Gannett Fleming declined to comment on pending litigation. Attorneys for CDM Smith and Larson Design Group did not immediately return a message on Monday.
The defendants have until Feb. 14 to submit their own expert reports.
CDM Smith, which was retained from 2005 to 2019 to inspect the bridge, breached the standard of care in several ways, according to Mrowiec: by not insisting on a new load analysis; failing to accurately measure the steel in the areas that had corroded; failing to identify fracture-critical elements (defined as steel bridge components whose failure could cause a partial or full bridge collapse); and failing to recognize the amount of asphalt on the bridge deck which caused it to weigh significantly more than what they thought.
Mrowiec called those alleged failures “substantial contributing factors to the collapse.”
Mrowiec reached a similar conclusion for Gannett Fleming, hired as a sub-consultant by Larson Design Group, which was tasked with conducting bridge inspections from 2020 to 2021.
Mrowiec said that as a new consultant to the Fern Hollow bridge, Gannett Fleming’s experienced bridge inspectors and engineers should have recognized the level of deterioration and followed up.
He was also critical of a team leader at Gannett Fleming, who he said failed to adequately review the work and analysis by a subordinate before signing off on it.
Mrowiec found that Larson Design Group also failed to identify the deficiencies in the work.
All three companies, Mrowiec wrote, had “multiple opportunities” to address the clogged drains, including lowering bridge condition ratings or directly communicating concerns to the city or PennDOT.
Mrowiec said the companies should have recommended the closure of Fern Hollow bridge to the city, which was aware of the span’s deteriorated state.
“The City of Pittsburgh failed to act; they took no legitimate steps to repair the deteriorated legs, clean the scuppers, verify the load analysis, request a new fracture critical inspection plan or close the bridge,” Mrowiec wrote.